From: Richard Prosser <rhprosser@gmail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Tue, 6 Oct 2020 12:26:58 -0700
Subject: Re: [EE] Looking for technique to record audio after level exceeds
	some value
Thread-Topic: [EE] Looking for technique to record audio after level exceeds
	some value
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There's an app called "SnoreLab" that does that sort of thing for snoring -
not sure if it would work in your application as it seems to filter non
snore noises. Or try one of the webcam apps (ipwebcam ?) , some of them
will trigger on noise or movement & play back a few seconds before & after
the event. With an old cellphone, you may be able to capture the flash.

RP


On Wed, 7 Oct 2020 at 08:18, Dwayne Reid <dwayner@planet.eon.net> wrote:

> Good day to all.
>
> I have a peculiar problem and I am hoping there is an off-the-shelf
> solution.
>
> It is approaching winter in Canada, which means that heating season
> is about to be on us.  One of the roof-top HVAC boxes on our building
> appears to have a gas ignition problem.  I hear explosions both quiet
> and loud when the heater turns on.
>
> This is obviously a gas ignition problem and we have called the
> service people a couple of times to get this fixed before the heat
> exchanger becomes damaged.  Specifically, what I think is that the
> fuel gas (Natural Gas) is accumulating in some area away from the
> ignitor, reaching some level higher than the Lower Explosive Level,
> then some traces of the fuel reaching the ignitor.
>
> But the service people can't see any problem and they are questioning
> whether I am just imagining the problem.
>
> What I would like to do is to set up one of my spare Android devices
> with the microphone in the heating duct.  But I need some way to have
> the device record just of few seconds BEFORE the explosion occurs as
> well as a few seconds AFTER the explosion occurs.
>
> Kind of like how pre-trigger works with a DSO.
>
> I've been looking but have not yet found an app that does this.  I'm
> hoping that someone here might have a suggestion.
>
> Note that I'm not married to the idea of using an Android device -
> just that's what I have handy.  I could also set up a laptop or
> netbook running Windows or DOS if I can find an appropriate application.
>
> I do have a fair amount of audio equipment here - mixers, preamps of
> various types, microphones ranging from really inexpensive to stupid
> expensive, audio recorders of various types.
>
> Problem is that none of the audio recorders that I have (DAT, SD-card
> based, Compact Flash based, etc) have the capability to continuously
> record a buffer, then capture several seconds before and after the
> loud sound occurs.
>
> Individual files with time stamps would also be desirable.
>
> IBM compatible Shareware or paid Android app is just fine.
>
> Suggestions gratefully accepted.
>
> dwayne
>
> --
> Dwayne Reid   <dwayner@planet.eon.net>
> Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
> 780-489-3199 voice   780-487-6397 fax   888-489-3199 Toll Free
> www.trinity-electronics.com
> Custom Electronics Design and Manufacturing
>
> --
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